Insight into the why you're doing it, is not necessarily going to lead to change. This could be a habit (all behavior fulfills a need even if it is unhealthy) If you get a rush when you spend, the brain pleasure center is activated. You can call it whatever you want if not shopoholic behavior. The fact remains - you feel that you're not in control of your actions. This in itself is a mistaken belief but the brain neuropathways had accepted the messages you send to your mind as true for the time being. Psychoanalysis or digging into the triggers/reasons is not a guarantee that you'd change your behavior. What is going to be helpful is to stay oriented onto the present moment and work with changing your brain neuropathways, which in turn will lead to a change in behavior.
It can be speculated as to why you act this way (but an online guess won't give you the solution) Perhaps the behavior is something you've witnessed in your childhood with your parents, it may be driven by the need to want to punish yourself even subconsciously because you may believe that money is evil. The habit is what you're living with and habits can change. The spending desire may be anxiety driven as you feel relaxed after spending.
You've mentioned having gone to counselors which is good as cognitive behavior therapy can me effective. You may want to look into hypnosis and working with someone specializing in NLP (neurolingusitic programming) as this modality can offer faster opportunity to change by targeting your subcouncsious mind and your belief system.